Date of Award

2020

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Molecular Biology

Abstract

Alcohol consumption is associated with increased risk taking and injuries leading to bone fracture. During bone fracture repair mesenchymal stem cells (MSCs) located at the site of injury differentiate into chondrocytes and osteoblasts to form a fracture callus. While most fractures heal without complication, studies show that alcohol abuse can lead to delayed fracture healing and fracture callus formation in both people and animals. Despite what is known about alcohol consumption in pre-injury pathologies like osteopenia and osteoporosis, the cellular and molecular mechanisms by which alcohol consumption inhibits fracture callus formation following orthopaedic injury remain to be elucidated. Here, we identified alcohol-mediated inhibition of MSC osteochondral differentiation as a potential mechanism underlying alcohol-induced deficient fracture callus formation. Using a clinically-relevant binge alcohol fracture model, we found that rodents administered alcohol had reduced early and late osteochondral-driven tdTomato expression in the developing fracture callus. While alcohol administration did not alter proliferation or apoptosis in the early developing fracture callus, rodents administered alcohol had significantly fewer proliferative fracture callus cells 9 days post-fracture when compared to saline controls. Primary MSCs co-cultured in alcohol showed a similar inhibition of osteochondral lineage marker expression that coincided with increased FoxO expression, nuclear translocation, FoxO/DNA binding, and target gene expression. FoxO1/3 knock-down significantly increased expression of pro-osteogenic transcription factor OSX and pro-chondrogenic transcription factor SOX9 in MSCs differentiated in the presence of alcohol. Interestingly, pharmacological inhibition of FoxO1/3 only increased expression of pro-osteogenic transcription factor OSX in the presence of alcohol. Overall, our results suggest alcohol inhibition of MSC osteochondral differentiation may be one mechanism underlying alcohol inhibition of bone fracture repair. Future studies will be necessary to determine the effectiveness of modulating FoxO1/3 to improve outcomes in alcohol-induced deficient fracture callus formation.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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